Sea Level Rise in Just 4 Key Points
Most people explaining climate change keep adding more and more information to their list of explanations. I seem to be going in the other direction. My opportunities to speak about rising sea level continue to grow. The more I give talks to diverse and large audiences, the more I have learned to distill the key points down to the essence — the minimum number to make an easily understood and irrefutable argument. Let me share them with you.
- The oceans are more than 1.5 degrees F (0.85 C) warmer than a century ago.
- Warmer oceans mean the Earth system has more heat energy, dictating that the glaciers and ice sheets will keep melting until the new equilibrium point is reached, as has happened for millions of years with natural cycles of climate change, such as the ice ages.
- As the ice sheets and glaciers get smaller, and the warmer ocean physically expands, sea level will keep rising for centuries, eventually tens of feet, as has happened in the past.
- As sea level rises, the shoreline will move far inland, since the average global shoreline movement is estimated at more than 300 feet for each foot of vertical change in sea level. This effect has already started, evidenced by the increased beach erosion, and accelerated flooding of low areas at extreme high tide.
There. That’s it. The entire case for sea level rise, flooding of all coastal cities, and the single greatest impact of global warming. This also becomes rather clear proof that this is no longer the natural cycle that has existed for all of human history. In a year of presentations in front of scientists, investors, law firms, government agencies, climate skeptics, even some professional contrarians and ‘tea-party’ members, no one has put a hole in the above points and logic.
The fact that the last time sea level was higher than the present, was 120,000 years ago is why we have such trouble believing it will happen. In our entire human record of civilization it has never been higher than now. It will keep rising for centuries due to the excess heat now stored in the ocean. The fact that the shoreline has never been farther inland in all of human history is the visible proof that we are in a truly new era. It does correlate with the change in levels of carbon dioxide, now at a level higher than in millions of years. More people are becoming aware of this fact that this new era of warmer temperatures, melting ice, and rising sea level is a departure from the natural climate cycles of the last few million years.
At our current ocean temperature sea level will keep rising far past the last high point 120,000 years ago. We now know that sea level back then reached about twenty five feet (8 meters) higher than now. (For a more complete explanation, see my book “High Tide On Main Street: Rising Sea Level and the Coming Coastal Crisis.”)
Simple physics says that we will EVENTUALLY reach sea level heights much higher than that. We simply do not know how fast it can happen. It could be two centuries or two thousand years. Largely it depends on how quickly we allow the warming to accelerate. Good reason to put lots of effort into two efforts:
A) Adapt to higher sea level and shifting shorelines, and
B) Slow the warming (also known as Mitigation)
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